The field of the invention pertains to integrated circuits (ICs), system on a chip (SOC) ICs, and processes and circuits for making and testing them.
In a mixed-signal SOC, a significant portion of the overall test time (and hence the test cost) is spent on testing the non-digital modules or IPs in the device. “IP” refers to an internal circuitry core or module (internal details not necessarily known to tester), and may generally refer to a circuit module hardware core or a soft core defined in design code. RF (radio frequency) circuit test time can even dominate SOC test time and be much higher compared to structural circuit test time and power management PM test/calibration time. When test time is in a production flow, it can limit achievable rates of production, which is expensive and problematic for manufacturers and consuming public alike.
RF testing is expensive because high pin count SoCs entail more test resources. Transmit tests may call for a complex demodulator to do tests for various modulation types EVM and standards coverages as in 802.11 (WiFi), and to do tests for BER (bit error rate) and other performances. Receive tests can call for RF test sources to test Sensitivity, Noise Figure, etc. Both TX and RX tests are even more complicated when multiple radios are integrated, such as Bluetooth, GPS, WLAN, FM, etc. Ports on the SoCs and on testing devices are likely to be limited in number. With multiple radios, co-existence tests are also likely to be called for.
This inconvenient and expensive test-time problem is further accentuated in devices with RF radios, wherein the tests require sophisticated instrumentation on the tester (in the form of stimuli sources and response loggers), further impacting the test cost. While highly accurate performance and specification tests could be intelligently replaced with coarser defect catching tests, (hence alleviating the need for expensive instrumentation on the tester), the test time still remains a bottleneck due to the need for applying these tests individually for the different radio IPs in an integrated SOC.
Consequently, new departures are needed to somehow address the above problems, and new types of circuits, devices and systems and processes of manufacturing and testing them would be most desirable.